The most incendiary part of a stinging letter from Senate Judiciary Committee leaders to Jared Kushner’s counsel, Abbe Lowell, is the committee’s disclosure that “other parties have produced documents concerning a ‘Russian backdoor overture and dinner invite’ which Mr. Kushner also forwarded.”

That sounds like a major piece of evidence in the broader context of Russian election interference and allegations of Trump campaign collusion with Russia.

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However, it is impossible to assess the significance of the email referenced without more information.

Who wrote that email? When was it written, i.e., how does it fit into the overall timeline of events?

To whom was it sent when Kushner was copied? To whom did Kushner forward it? Who produced it to the committee?

The committee has possession of the underlying email, but what Kushner did with it could reveal significant evidence that might not have been in the possession of the person who produced it.

In their letter to Lowell, Chairman Chuck Grassley (R-Iowa) and Ranking Member Diane Feinstein (D-Calif.) accuse Kushner of failing to provide other documents also requested by the committee.

In particular, they note that “other parties have produced September 2016 email communications to Mr. Kushner concerning WikiLeaks, which Mr. Kushner then forwarded to another campaign official.

Additionally, other parties also produced email communications with Sergei Millian, on which Kushner was copied. Millian, a Belarus businessman, is apparently identified as “Source D” in Christopher Steele’s dossier. They also note that Kushner has not produced any responsive phone records that “we presume exist.”

Beyond the Russia overture bombshell, their letter reveals several other dynamics at play in the congressional investigations of Russian interference.

A Bipartisan Show of Force

Of note, the letter is signed by both Grassley and Feinstein. A bipartisan committee leadership letter sends an unmistakable signal to Kushner’s team that the Senate Judiciary Committee is escalating its pressure.

Grassley’s participation brings with it a credible implicit threat of a subpoena. Under the committee’s rules, the “Chairman of the Committee, with the agreement of the Ranking Member or by a vote of the Committee, may subpoena the attendance of a witness at a Committee or Subcommittee hearing or Committee deposition, or the production of memoranda, documents, records, or any other materials.”

The measured tone of the letter still presumes Lowell’s goodwill. (“It appears that your search may have overlooked several documents.”) While the Committee’s patience has been tried, it has not been lost.

The message is clear: Stop playing word games and conduct a thorough and diligent search, or else a subpoena will be forthcoming. The committee gave a two-week deadline of Nov. 27, 2017. Grassley and Feinstein may not react well to Lowell’s public statement in response to the letter, reported here.

Jared Kushner, senior advisor to Donald Trump, in the Rose Garden of the White House, October 23, 2017 in Washington, DC. Win McNamee/Getty

In it, Lowell argued Kushner had provided the committee with all relevant documents that had to do with Kushner’s calls, contacts, or meetings with Russians during the campaign and transition, which he characterizes as the sum of the committee’s request.